get_pet_labels.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# */AIPND-revision/intropyproject-classify-pet-images/get_pet_labels.py

# PROGRAMMER: Qudus .A
# DATE CREATED:   15|01|23
# REVISED DATE: 15|01|23
# PURPOSE: Create the function get_pet_labels that creates the pet labels from
#          the image's filename. This function inputs:
#           - The Image Folder as image_dir within get_pet_labels function and
#             as in_arg.dir for the function call within the main function.
#          This function creates and returns the results dictionary as results_dic
#          within get_pet_labels function and as results within main.
#          The results_dic dictionary has a 'key' that's the image filename and
#          a 'value' that's a list. This list will contain the following item
#          at index 0 : pet image label (string).
#
##
# Imports python modules
from os import listdir


def get_pet_labels(image_dir):
    """
    Creates a dictionary of pet labels (results_dic) based upon the filenames
    of the image files. These pet image labels are used to check the accuracy
    of the labels that are returned by the classifier function, since the
    filenames of the images contain the true identity of the pet in the image.
    Be sure to format the pet labels so that they are in all lower case letters
    and with leading and trailing whitespace characters stripped from them.
    (ex. filename = 'Boston_terrier_02259.jpg' Pet label = 'boston terrier')
    Parameters:
     image_dir - The (full) path to the folder of images that are to be
                 classified by the classifier function (string)
    Returns:
      results_dic - Dictionary with 'key' as image filename and 'value' as a
      List. The list contains for following item:
         index 0 = pet image label (string)
    """
    # Creates list of files in directory
    in_files = listdir(image_dir)
    # Processes each of the files to create a dictionary where the key
    # is the filename and the value is the picture label (below).

    # Creates empty dictionary for the results (pet labels, etc.)
    results_dic = dict()

    # Processes through each file in the directory, extracting only the words
    # of the file that contain the pet image label
    for idx in range(0, len(in_files), 1):
        # Skips file if starts with . (like .DS_Store of Mac OSX) because it
        # isn't a pet image file
        if in_files[idx][0] != ".":
            # Creates temporary label variable to hold pet label name extracted
            pet_label = ""
        # Sets string to lower case letters
        low_labels = in_files[idx].lower()
        # Splits lower case string by _ to break into words
        split_labels = low_labels.split("_")
        # Loops to check if word in pet name is only
        # alphabetic characters - if true append word
        # to pet_name separated by trailing space
        for letter in split_labels:
            if letter.isalpha():
                pet_label += letter + " "
        pet_label = pet_label.strip()
        # If filename doesn't already exist in dictionary add it and, it's
        # pet label - otherwise print an error message because indicates
        # duplicate files (filenames)
        if in_files[idx] not in results_dic:
            results_dic[in_files[idx]] = [pet_label]
        else:
            print("** Warning: Duplicate files exist in directory:",
                  in_files[idx])
    return results_dic